L5 Developmental genetics

Question 1

What are the main causes of random mutations?

Answer 1

• Radiation (e.g. X-rays)
• Chemical (e.g. base modifiers)

These changes can be point mutations (single base-pair), deletion, insertion, translocation

Question 2

What are inherited mutations called?

Answer 2

Germline mutations

Inherited so from sperm or oocyte

Question 3

What is somatic mutation?

Answer 3

Somatic mutations are mutations that occur within our body.

Question 4

What are the two types of developmental genetics?

Answer 4

1. Forward Genetics (Mutagenesis).
2. Reverse Genetics

Question 5

What is forward genetics?

Answer 5

• Approach begins with observing a mutant phenotype
• Researchers then work to identify the gene or genes responsible for that phenotype
• Essentially, it moves from “phenotype to genotype”

Question 6

What is reverse genetics?

Answer 6

• Approach starts with a known gene or DNA sequence.
• Researchers then manipulate that gene (e.g., by mutating it) and observe the resulting phenotype.
• Therefore, it moves from “genotype to phenotype”

Question 7

What does mutagenesis mean?

Answer 7

This is the process of causing mutations

It can involve exposing organisms to mutagens, which are agents that cause mutations

Question 8

What are the major ways of targeting specific genes in reverse genetics?

Answer 8

1. Gene replacement
2. Gene Knock-out

Question 9

What is gene knock-out?

Answer 9

Complete removal of gene to determine its function.

Question 10

What is the major adavantage of CRISPR?

Answer 10

It works in any organisms

CRISPR is a different technology - can be used to knock-out or knock-in

Question 11

How does gene replacement work?

Answer 11

Gene replacement (knock-in) usually makes a small changes to the endogenous gene.

Question 12

What is the difference between forward and reverse genetics?

Answer 12

• Forward - Phenotype to gene
• Reverse - Gene - Phenotype

Question 13

What three ways of mutation that affects genes?

Answer 13

1. Changes in regulatory sequences (in the DNA that affects transcription)
2. Changes in non-coding sequences (of the transcript that may affect RNA splicing, stability or translation)
3. Changes in the coding sequence (may alter an important amino acid affecting folding of the protein or may create a premature stop codon)

Question 14

What is a domain?

Answer 14

A domain is a functional unit in a protein.

Question 15

What is a dimer?

Answer 15

A dimer is when two of the same protein bind together.

Question 16

Describe the process of a transcription factor binding to a DNA

Answer 16

1. DNA binding
2. Dimerization
3. Conformational change
4. Transcriptional activation

Question 17

What is a amorphic/non-functioning mutation?

Answer 17

• Missense (affect AA) mutation that completely inactivates the DNA binding domain.

Question 18

What is a hypomorphic/weakened mutation?

Answer 18

• Missense mutation that weakens DNA binding domains

Question 19

What is an antimorphic/dominant negative mutation?

Answer 19

• A missense mutation that destroys the dimerisation domain.

Question 20

What is the hypermorphic/overactive mutation?

Answer 20

• A missense mutation that results in activation that is independent of dimerization.

Question 21

What are the 4 types of mutations? (Muller’s Morphs)

Answer 21

Loss of function mutations:
1. Amorphic
2. Hypomorphic
3. Antimorphic

Gain of function mutation:
4. hypermorphic

Question 22

What is Muller’s morphs?

Answer 22

Types of phenotypes produced by mutations

Question 23

What are missense mutations?

Answer 23

A “missense mutation” is a specific type of point mutation within DNA

Question 24

Which type of Muller’s Morphs mutations are recessive or dominant?

Answer 24

Amorphic - Recessive
Hypomorphic - Recessive
Antimorphic - Dominant negative
Hypermorphic - Dominant

Question 25

What does mutations that result in the same phenotype despite being in different genes suggest?

Answer 25

Mutations that result is the same phenotype that are not in the same gene suggest that the genes function in the same pathway

Question 26

What are alleles?

Answer 26

Mutations that result is the same phenotype may be different mutations in the same gene. Mutations in the same gene are called alleles.

Question 27

What do reprter constructs help us to study?

Answer 27

Reporter constructs helps us to study gene and mutations in vivo.

Question 28

What is GFP?

Answer 28

Green Fluorescent Protein

Question 29

What is transfection?

Answer 29

The process of introducing foreign genetic material (like DNA) into cells

Question 30

How do you generate a GFP transgenic line?

Answer 30

1) Genomic DNA with all of the regulatory elements 2) Genetically engineer GFP onto the end of the last exon (gene fusion) or replace the gene (reporter construct) 3) Re-introduce this into the animal

Question 31

What is a transgenic line?

Answer 31

A cell line or organism whose genome has been altered by the insertion of foreign DNA.

Question 32

What are the uses for GFP transgenic lines?

Answer 32

- To follow expression of a gene or to follow the behavior of cells in vivo. - To follow subcellular localisation of a protein.